==================================================================
This Is SKY & TELESCOPE's AstroAlert for Occultations
==================================================================

Spectacular Pleiades Passage by crescent Moon Thurs. am, July 20,
eastern N.America, Caribbean

The Alcyone graze is one of the best of 2006 in the USA, with the
path passing from Texas to Michigan and Ontario; expedition planned
to observe Alcyone & SAO 76249 grazes near Gaines, Michigan, s.w. of
Flint, in the zone where the 2 graze paths overlap; there are many
other grazes, probably one near you (especially, grazes of Atlas in
British Columbia n.w. of Vancouver; of Pleione near Ogden, UT; of
Merope n. of Omaha and near Minneapolis; and of 6th-mag. 24 Tauri
near or over Louisville, Cincinnati, Columbus, & Akron) - NEW Web
sites are given for detailed path plots via google maps.

Also, TONIGHT there will be an occultation of 4.6-mag. epsilon
Piscium (ZC 146) by the 56% sunlit waning Moon. The northern-limit
graze path crosses eastern S. Dakota and central Minnesota (passing
very close or over parts of Duluth, but more likely over Superior,
Wisc.) at about 5:45 UT (12:45 am CDT). You can see it on the map
on p. 71 of the Jan. issue of Sky and Telescope; a total occultation
reappearance on the dark side will be visible from most of eastern
North America, with predictions given in the RASC Observer's
Handbook, and for some more North American cities on IOTA's Web site
at http://www.lunar-occultations.com/iota .

At the end I give some preliminary information about two good
asteroid occultations next week is also given, one visible from
eastern Virginia and the other from a path extending from Wyoming to
Chicago, s. Mich., & s. Quebec.
______________________________

General information about the occultations of bright Pleiades
stars Thursday morning, July 20, can be found on pages 68-69 of this
month's Sky and Telescope and on IOTA's main Web site at
http://www.lunar-occultations.com/iota/2006plnam/pleiadna.htm . The
latter gives predictions of total occultations of the brightest
Pleiades stars for hundreds of North American cities.

_______

My map on page 71 of the January issue of Sky and Telescope
shows the paths of the four brightest Pleiades stars crossing North
American on July 20, including the northern limit for the
spectacular graze of 2.9-mag. Alcyone from central Texas to Quebec.
Many more paths, of stars down to mag. 7.5, are in the RASC
Observer's Handbook for 2006. But these are small-scale maps; more
detailed maps are needed to get into the graze zones, which are only
about 2 km wide.

Interactive Web-based google interactive maps for several
Pleiades grazes are on two Web sites; you can use them to zoom in on
the paths to see exactly where they cross minor local roads, and
the paths can even be superimposed on satellite or aerial
photography. Unfortunately, Charlie Ridgway's site, mentioned in
the July issue of Sky and Telescope, can no longer be updated and
has no information about the July 20th Pleiades grazes. Most of the
graze paths can be found on Derek Breit's Web site at
http://www.poyntsource.com/BREIT_IDEAS/google/index.htm
but some in the northeastern USA can be found instead on Brad
Timerson's Web site at
http://www.fingerlakessythetics.com/occultations/GrazeMaps.html .
Timerson's site includes the interactive path maps for the grazes of
SAO 76188, 76191, and 76236; others are on Derek's site. If the
path you need is not on these sites, Derek Breit can add one if you
send him a request at breit_ideas@hotmail.com .

If you want to try one of the Pleiades grazes in your area, let
us know so we might help you set it up, and possibly find some more
observers who might help you. I'll distribute other expedition
plans as they become available.

There are other very good grazes, but the best during the
passage will be the one of the brightest Pleiad, 2.90mag. Alcyone,
whose path starts in central Texas, then crosses s.e. Okla., n.w.
Ark., s.e. Missouri (not far s. of St. Louis), s. Ill., Ind. (near
Lafayette & Howe), s.e. Mich. (over Flint), and Ont. (Bruce Peninsula
and on northeast from there). Bob Sandy, bobgraze@planetkc.com,
will probably try to observe it from Illinois or Indiana, while Hal
Povenmire and I plan to try to observe it from sites just west of
Gaines, Michigan, about 15 miles s.w. of Flint and about 50 miles
n.w. of Detroit. We selected this location because from locations
w. of Byron to the western and northern suburbs of Flint, the 2-km-
wide zone of visibility of the Alcyone grazing occultation overlaps
by over 80% the zone of visibility of another graze, of 7.5-mag. SAO
76249 that will occur an hour and 8 minutes after the Alcyone graze.
You can see this intersection zone on maps that Derek Breit has
posted at http://www.poyntsource.com/BREIT_IDEAS/Gaines.htm . Our
expedition will meet at 2 am EDT July 20 at the intersection of Ray
Rd. and S. County Line Rd., several tenths of a mile west of
downtown Gaines. On the DeLorme Atlas for Michigan, S. County Line
Rd. is labelled Sheridan Ave.; it marks the boundary between Genesee
County to the east and Shawassee County to the west. I have
annotated (to mark the meeting place) a copy of the detailed map of
the graze zones on Breit's Web site and will post that on my Web
site at http://iota.jhuapl.edu/exped.htm tomorrow (Mon.) afternoon.
The observation sites will extend westward from the meeting place
for one mile along Miller Rd. (the name of Ray Rd. in Shawassee
County) and for about 0.6 mile south from the meeting place along S.
County Line Rd. (or Sheridan Ave.). There are many other roads that
could be used in the large overlap graze zone from s.w. of Gaines to
Flint, but the aerial photography on the local live web site shows
many houses along those roads, the area is more suburban than rural;
the selected roads have fewer houses than the others (I hope to
arrive early enough to alert the residents of some of them, at least
the ones closest to the road that might detect us). Besides the
grazes, there are, of course, many total occultations that those who
get set up in time can observe; a few of them are listed below, as
computed for the observation sites just described (all
reappearances, R, are on the dark side of the 23% sunlit Moon):

EDT Event

2:33 1st R, 7.9-mag. SAO 76103, alt. 6 deg.
3:04 D of 4.1-mag. Merope on bright side, alt. 11 deg.
3:49-53 Alcyone graze, cusp angle 13N, alt. 19 deg.
4:56:02 R of 3.6-mag. Atlas
4:56:53 R of 5.1-mag. Pleione
4:57-61 SAO 76249 graze, cusp angle 14N, alt. 32 deg., Sun -13 deg.
4:59:19 R of 8.0-mag. SAO 76237, cusp angle 48N (this is near the
center of the SAO 76249 graze period so ignore it if you are
observing visually; video observers might want to try to get
their field of view positioned to image both events)
5:26 R of 7.0-mag. ZC 570, Sun alt. -8 deg. -last July 20th event

There are many other events that will be in a text file that I will
post on my Web site given above tomorrow afternoon. We expect to
keep one station set up at or very near the meeting place, so
depending on what you want to observe from the list above and your
setup time, you can arrive when you want. We don't know how cell
phone coverage will work in that area; you can try mine at 301-526-
5590; Hal Povenmire's at 321-794-0807, or Wayne Warren's at 301-518-
5754.

Mobile observers anywhere along the path across Michigan, and
with a little more difficulty in Indiana and possibly Ontario or
even e. Illinois, might also be able to observe both the Alcyone and
SAO 76249 graze, if they can move their equipment between the two
events in the 64 min. between the end of the Alcyone observing
period and the start of the SAO 76249 one. We decided to use the
major overlap zone in the area of Michigan described above since I
want to set up some unattended stations that I wouldn't have time to
move in other areas (this way, I can get both grazes with them), and
others don't want to miss some total occultations that will occur
during the time between the two grazes.

The Accuweather forecast for Flint, MI for the time of the
graze calls for about 50% clouds, which in my view is that they
don't know what will happen, just can't predict with any reliability
yet. I will be leaving home in Maryland, and possibly last chance
for e-mail contact, at about 10 am EDT Wed. July 19; those of us
from the Maryland - DC area will be carpooling to the graze (we'll
probably go in just my minivan, but if there are more than 3 of us,
we'll use two vehicles). If the Astro Meteo (Clear Sky Clock)
forecast is good for the Flint, MI area, we'll procede with our
plans to go to Gaines; we hope to get a motel room with wifi so that
we might have e-mail & Web (for weather information) access during
the evening before the passage. Of course, if the weather forecast
is not good for Michigan, we'll consider going instead to locations
in Indiana or even farther s.w. along the Alcyone path, or possibly
even to Ontario. If the weather forecast is poor for the Alcyone
path from Illinois to Ontario, we'll try one of the other grazes
instead in the Mid-Atlantic area from the list copied below, if the
forecast is reasonably good there.

Possible Pleiades Grazing Occultations

DATE Day EDT Star Mag % alt CA Location

Jul 20 Thu B 3:01 SAO 76158 7.9 24- 12 13N *Stedman,Greenville,Barco,NC
Jul 20 Thu X 3:42 SAO 76188 8.3 23- 20 13N *Warnbg,Indiana,PA;Syracs,NY
Jul 20 Thu B 3:42 24 Tauri 6.3 23- 17 13N *Loisv,KY;nCinci,Col,Akron,OH
Jul 20 Thu X 3:44 SAO 76191 8.5 23- 21 13N *near Somerset, PA &Utica,NY
Jul 20 Thu B 3:51 Alcyone 2.9 23- 19 13N Gaines,MI orHowe,Lafayette,IN
Jul 20 Thu B 4:37 SAO 76234 7.5 23- 33 16N *Coinjock, NC
Jul 20 Thu B 4:42 ZC 562 6.6 23- 34 16N Easton,MD;Richmond,VA;Sun-13
Jul 20 Thu B 4:59 SAO 76249 7.5 23- 32 15N Gaines, MI; Sun -13
Jul 20 Thu B 5:16 SAO 76259 7.5 23- 40 16N Waldorf&Annapolis,MD;Sun-8

This is almost the same list I distributed to Mid-Atlantic observers
in late May, but after the day I've added B or X to indicate that
the detailed graze path can be viewed with google maps on either
Derek Breit's Web site given above (B), or on both his and Brad
Timerson's web sites (X).

in other areas on July 20 (see Breit's Web site for path maps):

Local time Star Mag Location

2:22-2:30 CDT Merope 4.1 e.Nebr.,n.w.Iowa,Minneapolis,n.w.Wisc.
2:32 MDT-3:42CDT Pleione 5.0 n.Utah,n.w.Wyo.,s.e.Mont.,nwND,s.w.Man.
1:45 PDT Atlas 3.6 Brit. Columbia nw of Vancouver&Victoria

Notes for the Mid-Atlantic grazes:

Some grazes will not be attempted if expeditions are undertaken for
asteroidal occultations within 36 hours of the graze. * in the
Notes column means that no DC-area expedition is planned.

July 20: These grazes will occur during a spectacular passage of the
Moon across the Pleiades cluster that will occur Thursday morning, July
20, almost as good as the one on April 1/2, but the Moon will be waning,
not waxing, on July 20. And we don't have a bright graze passing near
DC, or anywhere in the Mid-Atlantic States, like we had with Maia early
in April. Nevertheless, the grazes below can be observed with small
telescopes and should be of interest to observers who don't mind losing
some sleep on a weekday morning.

24 Tauri = ZC 549. Besides passing over Louisville, KY and diagonally
across populous parts of Ohio (n. Cincinnati, near Columbus, near
Akron), the path also passes over St. Catherines, Ont., a very good
graze for those who can't travel a little farther n.w. to the
spectacular Alcyone graze path (see next).

Alcyone (eta Tauri = ZC 552): At mag. 2.9, this will be the most
spectacular Pleiades graze in the USA this year. It is quite distant
from DC, but if the weather forecast is favorable for Indiana, I'll
consider an expedition for it from the DC area; anyone interested in
joining such an effort please let me know.

ZC 562: At mag. 6.6, this is the best graze in the region, a
moderately bright star easy to see with small telescopes (but not
binoculars). The path passes over part of Charlotte, NC, and near
Greensboro. In Virginia, it passes over the southern and eastern
suburbs of Richmond. It crosses the Delmarva Peninsula a few miles
s.e. of Easton, MD (the closest point for an expedition from the DC
area) and near Milford, DE. It then crosses southern New Jersey and
Long Island, where twilight becomes noticeable, Sun alt. -9 deg.
The path crosses New England from the New Haven, CT area to the coast
of Maine, passing over Concord and Carlisle, n.w. of Boston, Mass.
By the time the path reaches Maine, the twilight will be quite bright
and will make observation a little difficult.

SAO 76259: At mag. 7.5, this is a good graze, too, still visible with
small telescopes and signicantly closer to DC- and Baltimore-area
observers than the ZC 562 graze. The path passes near Salisbury, NC
and then across central Virginia, crossing I-95 near Thornburg south
of Fredericksburg. It passes over the Southern Maryland Astronomical
Society's observatory in Nanjemoy, then extends northeastward to
Waldorf and Annapolis; sites in the semi-rural country between those
cities will probably be the closest access to a good graze from the DC
region during this passage. The path also passes over n.e. Maryland
and the n.w. suburbs of Philadelphia, where the twilight is becoming
rather bright. Nevertheless, observation might be possible in
northern New Jersey, where the path passes n.w. of Princeton and over
the Sperry Observatory in Cranford.
_____________________________________________________________________

Mid-Atlantic Asteroidal Occultations next week & during August 2006
dur. Ap.
Date Day EDT Star Mag Asteroid dmag s in. Location

Jul 24 Mon 21:25 TYC02670292 9.7 Huenna 5.9 3 4 e. Virginia
Jul 25 Tue 22:54 SAO 163453 8.4 Carmen 4.8 5 2 n&wNY,nOhio
Aug 2 Wed 5:21 2UC42184775 11.9 Alexandra 1.4 7 8 se N.Car.
Aug 5 Sat 20:35 TYC68042216 12.0 Fama 3.4 10 8 eVA,DE,NJ
Aug 11 Fri 1:00 2UC19282707 11.7 Zelia 1.1 7 8 NY,NewEng.
Aug 15 Tue 0:56 2UC21627363 11.0 Bondia 3.5 13 8 Pennsylvnia
Aug 21 Mon 4:42 TYC13101942 10.1 Vibilia 2.7 5 4 nOhio,w&nNY
Aug 25 Fri 5:58 2UC37477545 11.8 Charybdis 2.1 26 8 wSC,wNC,WV

Notes:

Updated paths, and often detailed finder charts, can be found at
Steve Preston's Web site at http://www.asteroidoccultation.com .
Very detailed maps for these events can often be found now on Derek
Breit's interactive Web page at
http://www.poyntsource.com/BREIT_IDEAS/google/index.htm (he has ones
now for the Huenna and Carmen events). Derek also has comprehensive
station lists for these events at
http://www.poyntsource.com/BREIT_IDEAS/index.htm . We'll be using
his station lists to plan coverage for the good Huenna and Carmen
events after I return from the Pleiades graze trip. Note that the
Carmen occultation path passes over southern Michigan (same region
as the Alcyone graze), a good event with a reasonably bright star.
That path also extends over Wyoming, Nebraska (Omaha near the n.
limit), s. Iowa, n. Illinois (Chicago n. of s. limit, Milwaukee n.
of n. limit but could have an event), s. Mich., s. Ont. (Toronto at
s. limit), and Quebec (s. limit along St. Lawrence River). Carmen
is an unusual M-class (metallic spectrum) asteroid that could have
an unusual shape (its light curve amplitude is relatively small, but
there was an unusual observation during another Carmen event in
Europe last month, so observations of the July 25/26 event are
important).
_____________________________________________________________________

David Dunham, 2006 July 16 evening

phones home 301-474-4722; office 240-228-5609; cell 301-526-5590